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Lieut. Louis J. Brunel, now in France, was commissioned on July 27, 1917, as Second Lieutenant in the Engineers Reserve Corps, assigned to the 7th U. S. Engineers, Dec. 10, 1917, and has been with the American E. F. since Mar. 26, 1918. He was assigned to the staff of the General commanding the 5th Field Artillery Brigade, as Engineer Officer, on Aug. 6, 1918. E. Ross Housholder writes that "the record for pontoon bridge building was broken Sept. 25, 1918, by Section A, Co. 4, 5th Engineer Officers' Training School, at Camp Humphreys, Va., of which I am a member. The time was 15 min. 11 3/5 seconds. We then proceeded to break the record for dismantling in 9 min. 57 1/5 seconds. The length of the bridge section was 200 ft. The post band was sent out to meet us, and we feel proud of this record. I have met quite a few A. I. M. E.

Jan 11, 1918

By AIME AIME

TWO technical sessions, an excursion through the Midwest refinery and a smoker, marked the first day of the meeting of the Petroleum Division at Casper, Wyo., on Aug. 28. Ninety-nine members and guests registered and there was an excellent attendance at 'all functions. The -local committee under the general chairmanship of J. C. Lindsay, general manager of the Western Pipe Line Co., had made every possible arrangement for the convenience and comfort of the visiting members and the Program Committee under E. L. Estabrook, vice-chairman of the Petroleum Division, had brought together a most interesting series of technical, papers. The meeting centered mainly on the various features of the Salt Creek field but there were also contributions from the technology of production in California, the Mid-Continent, and the Texas fields. The opening session was called to order by Mr. Estabrook at the Townsend Hotel on Friday morning. The members and visitors were welcomed appropriately by Ex-Governor B. B. Brooks, president of the "Rocky Mountain Oil and Gas Association, who recalled the changes that had taken place as Casper, a frontier cow town, became a thriving oil metropolis. F. Julius Fobs, chairman 'of the Petroleum Division, responded and then took the chair. He introduced H. Foster Bain, Secretary of the Institute, who expressed the regret of those members members who found it impossible to stop over en route to Salt Lake City and his own pleasure at meeting with the Division in the field. Following these introductory ceremonies the technical session began with a "Sketch of the Geological Formations of Central Wyoming," presented by J. G. Bartram of the Midwest staff. It was brief and to the point and contributed greatly to the easy under¬standing of the succeeding papers by those unfamiliar with the region. The talk was illustrated by a large scale columnar section -and a copy of the excellent, geological map of the State recently issued by the U. S. Geological Survey.

Jan 1, 1925

By Max Hebgen

Within the State of Montana the streams rise in the high mountains at. an elevation of from 5,000 to 8,000 ft. These streams leave the State line both east and west at elevations from 3,500 to 2,400 ft. It is, therefore, apparent. that all these streams have an average fall of 3,000 ft. within the confines of the. State, and many opportunities are presented on all streams. for the development of power, by taking advantage of the natural fall. It is probable that 1,000,000 h. p. can :be developed in the State of Montana. I. NATURAL FEATURES OF STATE AFFECTING POWER DEVELOPMENT. The main. range of the Rocky mountains, forming the Continental Divide, cuts the State of Montana into two parts. The eastern part is drained by the Missouri river and its tributaries, the Madison; Jefferson, Gallatin and Yellowstone, rivers. The western part is drained by tributaries to the Columbia river, the Clarks fork and the Kootenai river. The Clarks fork in turn is formed by the junction of Missoula and Flathead rivers, the latter, draining Flathead lake. The western part of the State. is mountainous and the eastern part is comparatively level. As a natural result the rivers in the western part are capable of generating large amounts of power, while in the eastern part of the State natural power sites are much fewer and farther apart. It also follows that in the mountainous districts large amounts of power are required for the mining industry, while in the eastern part of the State, which is principally devoted to agriculture, power is required in smaller quantities. ?

Jan 8, 1913

By A. G. H. Andersen, A. W. Kingsbury

SILICON bronzes containing iron are used to a considerable extent in industry, under the trade name of P.M.G. alloys. Various classes of wrought alloys fall in the composition range 1.5 to 3.5 per cent silicon, and 0.5 to 2.5 per cent iron. Castings may contain as much as 6 per cent silicon and 3 per cent iron at present. The constitutional diagrams of these alloys are thus of considerable practical importance. Copper-silicon-binary alloys have been thoroughly investigated by a number of workers, the latest reports being those of C. S. Smith' and of A. G. H. Andersen .2 Although much work has been done on iron-copper alloys,3 recorded investigations on the copper-rich copper-iron binary constitutional diagram are not numerous. Tammann and Oelsen4 determined the solubility limits of iron in copper by means of magnetic measurements, and found that the solubility of iron in copper amounts to a fraction of one per cent at 400°C., increasing slowly to one per cent at 800°C. From 800°C., the solubility increases rapidly and attains 4 per cent at 1100°C. Hanson and Ford," using electrical resistivity measurements and the microscope, determined a somewhat different solubility limit. Of earlier X-ray works on the copper-iron system, very little has been published. The work by Bradley and Goldschmidt6 on copper-iron-aluminum alloys includes some information on the copper-iron binary. These investigators conclude that substitution of iron in the copper lattice decreases the spacings, which is contrary to the evidence of the present work. Hanson and West7 have investigated the ternary alloys of copper with iron and silicon. Although their diagrams are valuable contributions to the understanding of these alloys, they did not recognize the kappa phase,1,2,7,8 and their diagrams do not everywhere conform to the phase rule. The present work contains a check by means of X-rays of the solid solubility limit of iron in copper, and an X-ray investigation of the ternary-phase diagram, which, owing to present conditions, it became necessary to curtail considerably. PREPARATION OF SAMPLES Castings weighing about 75 grams were melted under vacuum. The charges were made up of ingot iron, copper cathodes from Laurel Hill, and refined silicon supplied by the Electrometallurgical Co. Alundum crucibles were generally used. The exceptions were alloys 77 and 78, which were melted in graphite crucibles. The ingots were annealed at 800°C. for one week, then samples were cut for chemical analysis. Longitudinal sections of the binary alloy ingots were hammered into plates h in. thick. Wherever possible, these plates were homogenized at temperatures ensuring

Jan 1, 1942

By William H. Spice

Drilling activities in South Central Texas for the year 1945 continued the steady increase over the past two years, while new fields discovered for the year included four new gas fields and one field extension. In the 30 counties included in this area, which comprises district No. 1, Oil and Gas Division, Railroad Commission of Texas, 141 exploratory wells were completed, compared with 61 drilled in 1944 and 29 drilled in 1943. Of these 141 tests, 55 were field well and 86 were wildcats; 38 were completed as oil wells, S as gas and gas-distillate producers, and 95 were abandoned as dry. Atascosa and McMullen Counties were the most active in the district, accounting for 73 of the wells drilled.

Jan 1, 1946

By WILLIAM J. LINNEY

MAGNETITE ore from Lyon Mountain, so- called "Low Phos Chateaugay," has long been known to the iron and steel industry for its almost complete absence of impurities. These magnetites occur along the northern foothills of the Adirondacks in several parallel and folded stringers which are continuous for several miles, striking generally northeast-southwest and dipping usually over 45° to the northwest, or roughly toward the St. Lawrence River. Ore of minable thickness is found in shoots of various sizes as to length and breadth, but of undetermined and possible great depth.

Jan 1, 1943

By E. D. Gardner

AGAIN in 1945, the fourth year of World War 11, the American mining industry met the necessary demand made upon it for metals. Lack of labor prevented full production in some districts; maximum output, however, was maintained with the man power available. Development work and maintenance of mechanical equipment were neglected in favor of immediate production. Drafting of the younger men continued throughout the year, and the loss of personnel to war industries with higher wage rates continued up to "V-J" Day, Aug. 14. Labor shortages were more critical in 1945 than in 1944 though the man-power situation eased for some districts in the last quarter of the year. The trend in mining for the most part was to increase tons per man-shift by continued increased mechanization and refinements in methods and practices; larger equipment was installed where practicable. Labor shortages, together with the current higher wage rates, have advanced mechanization several years ahead of normal progress. The manpower shortage and the employment of inexperienced men had the effect of decreasing the average efficiency of the individual workman, but this condition was largely balanced by improved organization, greater efforts to improve labor relationship, and increased use of incentive pay systems. Safety instruction was emphasized, personnel contacts were increased, and more frequent foremen meetings were held to clarify contract agreements. Many of the large companies maintained schools to train green workmen.

Jan 1, 1946

By John A. Emery

The Pea Ridge iron ore deposit near Sullivan, Missouri, is a dike-like mass of magnetite enclosed in Precambrian porphyries. The ore body tops at the Precambrian surface at a depth of 1300 feet below the present surface and extends to an unknown depth. It dips nearly vertically, intersecting the dip and strike of the enclosing porphyries at an extremely sharp angle. Faulting, both pre- and post-ore, appears to be of minor consequence, and present knowledge indicates that no preferred structural conditions existed prior to emplacement. The ore body is composed of magnetite with specular hematite, quartz, apatite, and pyrite occurring as accessory primary minerals. Specular hematite in appreciable quantities occurs on parts of the cap and the footwall of the ore body. Fresh porphyry breccia is enclosed in the magnetite along the hanging wall and in the western portion of the ore body. Hanging-wall quartz-amphibole and footwall quartz-hematite occur as replacements of certain porphyries. Further alteration has caused sericitization of parts of these zones. The ore deposit is interpreted as having been formed essentially by a single injection of a magmatic differentiate with hydrothermal end phases forming the quartz-amphibole and quartz-hematite portions of the deposit.

Jan 1, 1968

By H. Rush Spedden, A. M. Gaudin

IN the belief that a critical study of its operating problems might be a sound investment, the Cuban American Manganese Corporation initiated an ore-treatment research in cooperation with the Massachusetts Institute of Technology. One of the early objectives of this research naturally became the relationship of the microscopy of the Cuban ores of the Corporation to their flotation treatment. The operations in Cuba have already been described by F. S. Norcross, Jr.7 and the laboratory study of manganese oxide flotation goes back a number of years .4 Broadly speaking, the difficulties encountered in the flotation of manganese ores are that the consumption of reagents is extremely high, the concentrate contains more silica than is desirable and the tailing losses are relatively high. An appreciable betterment on any of these scores would achieve a definite betterment in costs, quantity of minable ores, and quality of product. The microscope study discussed in this paper was made on samples from the Quinto mine, from the Ponupo mine, and from mill products at various stages of passage of the ore through the mill. The writers have had access to Company records and in particular to the petro¬graphic studies made on thin sections of ore by the late Professors R. J. Colony and Philip Krieger, of Columbia University. They acknowledge their debt to both of these men for the help derived from the reports. Manganese oxides are black, friable, smudging. It is, therefore, very difficult to judge operations by inspection. The mineralogy of manganese compounds seems to be confused, and the authors believe that many more minerals have been described than actually exist. Much of this difficulty is due to the prevalence of the structural conditions that will be discussed further in this paper; namely, the porosity and the friability of the ores, and the extremely intimate association of minute manganiferous mineral crystals with impurities of various sorts. By all odds the most important manganese mineral in Cuba is the one that in this paper is called "psilomelane." The name "psilomelane" has been used in so many different ways that the choice of it for this ore may not be approved by all. However, it seems to be the best under the circumstances. This mineral accounts for about 97 per cent of the manganese in the ores of the Quinto and Ponupo mines and in the mill feed. The remaining odd 3 per cent consists mostly of pyrolusite together with minor amounts of other manganese oxide minerals. DESCRIPTION OF PSILOMELANE Aggregate Structure In grains or lumps, psilomelane has a characteristic fibrous appearance and seems

Jan 1, 1942

By A. G. Weber, R. L. Ledbetter, A. L. Hicks

A procedure which makes use of both analog and digital computers has been developed for predicting the pressure-production behavior. of water-drive reservoirs. The electric analyzer is used for matching the past pressure and production history of the reservoir and inferring the physical characteristies of the aquifer. When the history has been matched, a .set of base curves called influence functionce" are derived and the future behavior of the reservoir is calculated from these curves. INTRODUCTION Electric analog methods are particularly well-suited for complex water-drive problems. Like all other methods of analyzing water-drive reservoirs, however, analog methods are subject to certain limitations. One of the more obvious and serious of these results from inaccurate or insufficient knowledge about physical characteristics of the reservoir and aquifer. However, it is not insurmountable because the unknown characteristics can usually be inferred from the reservoir's previous behavior. Simons and Spain have shown that even with scant reservoir data and limited production history, electric analyzer studies can provide useful and reliable results. Aside from this limitation on analyzer predictions, the main disadvantage has been lack of a technique for keeping predictions abreast of latest production forecasts. Pressure behavior of a reservoir depends on the rate at which fluid is withdrawn; it is therefore necessary to specify the future withdrawal schedule before the future pressure behavior can be calculated. Conventionally, the electric analyzer predicts pressure behavior for a specific production schedule. If this schedule is abandoned in favor of some new one, as is frequently the case, either the study must be rerun or results adjusted in some manner. The usual procedure is to predict pressures for several different forecasts covering a wide range of production rates. Pressures for specific rates other than those studied can then be approximated by interpolating between the analyzer predicted curves. However, reliability of this type of prediction is doubtful. This paper describes a technique for predicting future behavior of water-drive reservoirs that retains all advantages of electric analyzer analysis and eliminates the main disadvantage. That is, the analyzer is used conventionally to infer unknown reservoir parameters from the pressure history, but not to predict the future behavior directly. Instead, a derived set of base curves, called influence l'unctions, can be used to calculate future behavior for any production schedule.

By AIME AIME

The American Society of Mechanical Engineers.-The semi-annual meeting of the American Society of Mechanical Engineers will be held in Detroit, Mich., June 23-26. A session will be devoted to hoisting- and conveying-machinery; and many other subjects will be treated in professional papers, among which are . Clutches (with special reference to automobile clutches); The Thermal Properties of Superheated Steam; The Horse-Power, Friction-Losses, and Efficiency of Gas- and Oil-Engines; A Journal-Friction Measuring-Machine; A Simple Method of Checking Conical Pistons for Stress, and The By-Product Coke-Oven. The usual receptions will be held and excursions will be made to manufacturing plants, the slip-building yards, and various points of interest in and around Detroit. Among the excursions' planned is one to the University of Michigan at Ann Arbor. The Gas-Power Section of the Society will hold a session, and the Society for the Promotion of Engineering Education and the Society of Automobile Engineers will hold meet-

Jan 5, 1908

By F. L. Bosqui

The history of the development of gold metallurgy in South Africa is divisible into two periods: That preceding the introduction of the cyanide process on a commercial scale in 1890; and the 24 years intervening between that important event and the present time. The period between the discovery of the banket reefs of the Witwaters-rand and the year 1890 was one of phenomenally rapid progress in mining development, but of no special interest to the metallurgist, There were no strikingly original or distinctly local advances in the treatment of gold ores. Californian practice in stamp milling and amalgamation prevailed, in mills ranging in equipment between 5 and 50 stamps, operating within a wide range of efficiency, and under the trying conditions usually encountered in a new and isolated field. The somewhat incomplete records of gold output of that period show that in December, 1887, there were 20 producing companies in the Witwatersrand district, of which 10 had mills, the largest being of 20 stamps. The only official record of returns for May, 1887, was that of the Wemmer mine, whose modest achievement with a 5-stamp mill was 100 tons crushed, producing 887 oz. 3 dwt. of gold. This is interesting in view of the present-day output of this field, which in 1913 reached 8,430,998 oz. The rapid increase of production during this first period (May, 1887, to January 1891) is shown by the following summary for the year 1890:1 Total tone crushed.................................. 702,828 Number of stamps in operation....................... 1,046 Average number of tons crushed per stamp per day..... 2.36 Yield of gold, ounces................................ 494,817 Yield per ton, pennyweights.......................... 13.36 The stamp duty ranged between 11/2 and 4 tons per day, according to weight of stamp, fineness of screen, and operating skill available. The prevailing weight of stamp was about 900 lb., and the screen, 900 meshes to the square inch.

Jan 1, 1916

By H. J. Struth

AN unusual engineering achievement in the Gulf Coast last year was the drilling of a wildcat well in the swamps of Louisiana, using direct current. More unusual was the fact that it was necessary to house a diesel engine and generator on a barge in order to supply power. The remoteness of the well made it necessary to transport living quarters and drilling equipment to the location by means of barges, and involved the digging of a canal from a lake to the location, approximated one mile. The drilling equipment used on this well consisted of two generating units, each having one 210-hp. six-cylinder @$-in. bore type VDMA, 600 r.p.m. diesel engine, direct connected to a type CD-169, 125-kw., 250-volt direct current generator, which in turn is direct connected to a type CD-105, 15-kw. 250-volt exciter. One of these motors operates the draw works, one the mud pump, and one a duplicate spare. The generating equipment on the barge was approximately 250 ft. from the derrick, the control wires being brought from the derrick to the generator barge enclosed in a standard fire hose. This is an original idea for confining the con- 11.01 wires in one cable; obtaining minimum space and ample protection. Both control and power lines were suspended on poles. This well was at Lake Grande Ecaille Dome, which was located by seismograph in 1928. Fig. 1 shows the derrick, power barge and living quarters where direct G. E. current was used with rotary drilling equipment.

Jan 1, 1932

By J. C. Bradley

The relation of annealing temperature to conductivity of copper wire has been determined. Conductivity hard was 98.26 per cent. After a 10-min. heat,ing at 200" C. it was 98.69. By annealing 10 min. at 300" C. a large increase, to 100.93, occurred. Maximum conductivity, 101.15, was attained after a 500" C. anneal; thereafter it decreased to 100.53 after a 950" C. anneal. If copper is gassed the decrease is much more than this. Material and Method The work was done on high grade electrolytic copper, 99.942 per cent, copper plus silver, silver 0.0008 per cent. It was hot-rolled to 1/4 in., then cold drawn to 0.080 in. The wire was cut into 25 5-ft. lengths and numbered 1 to 25 as cut. Four samples were tested hard. The others were wound into 5-in. diameter coils. For the 100" C. heating a coil was put into water, the water brought to . boiling, and the wire kept at this temperature for 10 min. For the higher temperatures the coils were placed in envelopes of sheet copper, a little water added, and the envelopes sealed by folding over the edges twice, and hammering them together. This kept the air out very well. The envelope and wire were brought to the desired temperature; this was maintained for 10 min., then the whole was water-quenched. Results Data from the tests are shown in the table and plot (see Fig. 1); conductivity is referred to the International Annealed Copper Standard at 20" C. Conductivity hard is considerably less than conductivity soft.1 The increase is sharp when the wire anneals. The maximum, 101.15 per cent, in the particular material used, comes at 500º C.; thereafter the conductivity falls to 100.53 per cent. after 950" C. annealing, a drop of 0.62 per cent.

Jan 1, 1927

By S. B. Casey

[ ] IN 1880, an electric arc was struck over metal for the first time to experiment with controllable melting. The glare of this arc has reflected on the stacks of the steel industry and continued to light the path of steelmakers in their never ending quest -for faster, more economical, and better ways of producing steel. William Siemens is credited with first employing the electric arc to melt metal in a closed hearth and produce basic metallurgical reactions. By the turn of the century, an Italian, named Stassano, was experimenting with ore reduction by the electric arc. In 1899, Dr. Paul Heroult, in France, used the direct arc principle for producing ferro-chromium. His experiments quickly led him to develop a dosed-top arc furnace for the production of steel, and his first commercial shipment was recorded in December, 1900. American steelmakers, quick to sense the possibilities of this method of melting, invited Heroult to our shores, where, in 1905, he was responsible for installing the first arc furnace on the North American continent. This furnace, at Sault Ste. Marie, was built for ore reduction. But Charles Holcomb, founder of Holcomb Steel. Co. of Syracuse, N. Y. contacted Heroult in 1905 and contracted for the first American direct-arc electric furnace for steelmaking. On April 5, 1906, the first heat was tapped from this 3-ton unit. The furnace was basic lined and powered by a single-phase, 500 kw generator, -producing high amperage at low voltage. It is interesting to note that, although the first few heats were made with cold charges, subsequent heats were duplexed. R. H. Bully, first superintendent of Holcomb Steel, persuaded the directors to purchase the unit to effect a more economical and efficient means of making tool steel by duplexing prime melting in a combustion fired furnace, and transfer of hot metal to the arc furnace for temperature adjusting, refining, and adding carbon and alloying elements. Today, duplexing is foreseen by some as the steelmaking process of the future. The promise shown by America's first arc furnace for ingot production quickly led to the purchase of a similar unit by The Firth Sterling Steel Co., in 1909, and to the purchase of the first arc furnace for production of steel castings, by the Treadwell Engineering Co., in 1911. From its humble start in 1906, production of arc furnace steel has never ceased to increase its yearly percentage of total steel production in the U. S., although certain other methods have declined or almost disappeared. By its ability to be used intermittently, the arc furnace gained favor and enhanced its reputation during depression days. When the attack on Pearl Harbor plunged us headlong into the long days of World War II, the arc furnace stood ready, flexible enough to be overburdened hearth wise 30 pct and power wise 25 pct, pouring its endless flood of alloy for the guns, tanks, ships, and planes which ultimately brought victory. During the post war boom, the now, proven virtues of low initial cost, faster installation, better yield, improved availability, and lower operating cost, enabled industry-particularly the small, new, independent producers-to locate strategically and profitably to meet the demand of an America that had been starved for new homes, appliances, cars, and highways. In the Korean police action, the arc furnace again proved itself by providing the latest alloys metallurgists could develop to meet the demands that the jet age and the innovations of guided missiles required. In today's peacetime prosperity, the arc furnace is continuing to provide the economic flexibility required to meet an ever increasing demand for better steel in the face of mounting costs, scrap shortages, and pressure toward decentralized location of industry.

Jan 1, 1961

By Steven Mitchell

BACKGROUND Homestake Mining Company began milling operations at the Bulldog Mountain Mine near Creede, Colorado in 1969. The Bulldog Mill, rated at 350 tpd, produces a bulk flotation condentrate assaying about 180 oz/T Ag and 20% Pb, from heads of about 16 oz/T Ag and 2% Pb. The circuit is straightforward with two-stage grinding to 1-5% plus 65 mesh, followed by rougher and cleaner flotation. Reagents used are Z-6, Z-11, Aerofloat 242 and Aero Promoter 404, with an Aerofroth 65-MIBC mixture for a frother. Additional information on the geology, mine and mill are available in references (1) and (2). A flow sheet for the mill and CIP plant together is attached as Figure 1. Final flotation tailings normally vary from 1.5 - 2.0 oz/T Ag. These tailings are cycloned to produce sand for underground backfill. After cycloning, the sands are repulped and given a final scavenger float. This sand scavenger recovers a small additional amount of silver which recycles back to the main flotation circuit. The tailings are recycloned and pumped to the mine or, if the mine cannot accept sand, to tailings. The majority of the silver in the flotation tailings exists in the fine fractions; cycloning upgrades the slimes and lowers the assay of the sand. The sand, after scavenging, typically assays 0.5 oz/T Ag, and the slimes assay about 3.0-3.5 oz/T Ag. From 1969 to 1976 all of the slime tailings and the sand tailings not used underground were impounded in a tailings pond located about

Jan 1, 1983

By William Gilman

IN the past five years, and without much fanfare, Turkey has emerged as a significant figure in the world mining picture. This has been accomplished by a five-year plan now in its last year. A second five-year plan is already under way, ahead of schedule. It will concentrate even more than the first in developing Turkish mines in order to increase present exports of coal, chrome ore, and copper, and to develop new mineral exports as well. To be fully understand the republicic?s mining program should be considered as something more than merely tapping rich resources in the East along the Aegean Sea, in the North among the mountains descending to the Black Sea, and in the West at the foot of the Taurus Mountains. It should also be viewed in the light of a strong nationalist policy with many aspects of state socialism. Turkey declares frankly that all mineral re- sources belong to the nation and all exploitation should be by the state for the twin purpose of modernizing the state and securing foreign exchange for the state by exports. Accordingly, the principal mines are state-operated and a few lesser enterprises, although not state-owned, have at least been put in the hands of Turkish capital.

Jan 1, 1938

By J. H. East, E. R. Maize

INTRODUCTION PROBABLY no other type of equipment is now being introduced into American underground mines about which less is known and about which there is more misinformation than the Diesel mine locomotive. Any equipment installed underground brings with it hazards that were not present before, and it is the purpose of this paper to show that Diesel-powered equipment can be used with safety in underground mining if certain feasible but very important precautions are taken. Diesel locomotives are not new in underground mining, since they have been used successfully in European mines for at least 19 years, but their use in American mines is exceedingly limited; so far as is known, only five Diesel mine locomotives are operating at present in United States mines. Diesel locomotives were permitted underground in Great Britain for the first time in 1939, and the rapid increase in the number in use in those mines, testifies to their safety and efficiency. More than 1300 Diesel mine locomotives are in use in European mines, according to the latest statistics; these locomotives are employed in coal, iron, lead-zinc and mercury mines. So far as is known, the Diesel mine locomotive has not yet caused an explosion or mine fire, and has not been the cause of any fatalities from toxic gases in the mines in which it has been used. ADJUSTMENTS OF DIESEL ENGINES FOR UNDERGROUND USE A Diesel engine adjusted to work in an underground mine should not be confused with the same engine adjusted for use outside the mine. Adjustment of the air:fuel ratio for engines that are used on the surface is intended to give the maximum fuel economy, and little or no attention is given to the chemical composition of the exhaust gas produced. Many such engines are poorly adjusted and perhaps poorly maintained, with the result that the engine emits smoke in quantity as well as the disagreeable odor familiarly associated with Diesel engines. The air:fuel ratio in the case of Diesel engines operated on the surface is generally around 15:1; that is, 15 lb of air to burn 1 lb of fuel. Diesel engines adjusted to work underground usually have an air:fuel ratio of about 20:I, as at this ratio the minimum quantity of toxic gases is given off in the engine exhaust. Diesel engines operated underground must be maintained in better condition than similar engines used on the surface; otherwise, the smoke emitted in the exhaust becomes objectionable if not unendurable. Practically normal air is required for safe operation of Diesel engines underground or in confined places; failure to provide virtually normal air for Diesel engine operation is almost certain to result in trouble. Bureau of Mines engineers have determined that the air in which a Diesel operates in confined places should contain less than 1/2 pct of carbon dioxide and at least 20 pct of

Jan 1, 1947

By D. R. Walker, M. C. Shaw

Dimitri Kececioglu (Allis-Chalmers Manufacturing Co., Milwaukee)—The idea of applying metal cutting theory to comminution and vice versa is very impressive. Among others, the demarcation of wheel-grinding data into two regions, namely Kick's and Rittinger's, draws attention here. A study of Figs. 6 to 9 shows the following: In Fig. 6, 1 point out of 8; in Fig. 7, 4 points out of 26; in Fig. 8 only 1 point out of 13; and in Fig. 9 practically none out of 13 points fall out of curve No. 2. Also when grinding particles smaller than 5x10." in. it is difficult to measure very accurately the grinding forces, chip geometry, and particle size. In view of the above it would be difficult to make a positive and distinct demarcation of the Wheel-grinding data into two regions, namely, Kick's and Rittinger's. The idea of using machine grinding to determine the comminution properties of materials is indeed unique. The following cautions come to mind, however, regarding applicability of machine grinding data to comminution: 1—Grinding gives uniform particle size, whereas comminution gives a variety of particle sizes in the same process. The fact that grinding gives uniform particle size is not necessarily an advantage because in comminution the overall energy under actual comminution is desired and comminution invariably results in the production of a variety of particle sizes. 2—In grinding, a small particle is ground off a comparatively large surface. In comminution small bodies are broken down to smaller bodies. This makes it difficult to establish a concept of reduction ratio in machine grinding. 3—The mechanics of machine grinding involve direct shearing action under very high strain and comparatively high compression at the shear zone, whereas: comminution involves direct dynamic compression and surface friction with comparatively little strain and shear. Consequently the mechanics of machine grinding appear to be different from those involved in comminution. Hence one might arrive at erroneous con- clusions when comminution characteristics are eval-uated from machine grinding results. It is noticed also that functions other 'than Eq. 16 which do not involve the concept of direct proportionality of useful energy input to new surface area created (Eq. 2 and particularly Eq. 12) may be derived to fit the, data of curve No. 2. One such relationship may be u = ct-", where c is a positive constant and n is a positive constant less than unity. This, of course, is made possible because data of a very small range. of particle size are being fitted by the curves of No. 2 and the hereby suggested relationship. A sound comminution theory should be applicable to a relatively large range of particle size. George B. Clark (Department of Mining Engineering, University of Illinois)—While the experimental work of Walker and Shawin this article is of intrinsic value in revealing certain fundamental aspects of machine grinding, milling, and related processes and in adding to the store of information concerning the comminution of solid materials by this particular process, it appears doubtful that the results of their research can be employed to verify either Kick's or Rittinger's theories. Both these laws were originally developed and proposed on the basis of very simple, idealized hypotheses. The creation of parallel idealized physical laboratory conditions which would be required for either their proof or disproof appear to be well beyond the scope of human ingenuity, at least at present. One great weakness of the imputed verification is that the spread of the points plotted on the graphs is not sufficient to permit accurate 'curve fitting. The range of particle sizes included in the belt and wheel grinding is not extensive enough to show any general trends, particularly for the horizontal portion of the curves, said to represent Kick's laws. That the milling; grinding, and turning data obtained by Walker and Shaw for both metals and minerals happen to comply with. certain interpretations of these two theories under certain specialized conditions

Jan 1, 1955

By AIME AIME

THE technical material in hand and the plans under way for the 141st meeting of the Institute clearly indicate a well-rounded program of unusual excellence. The meeting will be held in the Engineering Societies Building, Feb. 15 to 18, and while it is too early to announce definitely the time of the various sessions much of the detail has been organized up to that point. Every group in the Institute membership will find much of special interest, and several features should prove generally attractive. The various committees in charge of the lighter side of the meeting are hard at work to emulate the standard established last February In this connection and in this paragraph it will suffice to say-there will be a Smoker-dinner! The Committee on Mining Methods plans two sessions for which these papers are in prospect:

Jan 1, 1932